U.S. patent application number 11/947566 was filed with the patent office on 2008-06-12 for inflator.
This patent application is currently assigned to DAICEL CHEMICAL INDUSTRIES, LTD.. Invention is credited to Atsushi Hatomoto, Akihisa Ogawa, Shinichiro Ukita, Haruhiko YAMASHITA.
Application Number | 20080136153 11/947566 |
Document ID | / |
Family ID | 39110741 |
Filed Date | 2008-06-12 |
United States Patent
Application |
20080136153 |
Kind Code |
A1 |
YAMASHITA; Haruhiko ; et
al. |
June 12, 2008 |
INFLATOR
Abstract
The present invention provides an inflator including: a
pressurized gas filled with a pressurized gas and having a first
end and a second end; a gas generator being connected to the first
end, and including therein an ignition device and a molded article
of a gas generating; a diffuser portion connected to the second
end, and being provided with a gas discharge port; a communication
path provided between the pressurized gas chamber and the gas
generator and closed by a rupturable plate; a cap provided to cover
the rupturable plate from the pressurized gas chamber side and
having a plurality of gas holes formed at a circumference thereof,
the minimum diameter (d min) of the gas hole being equal to or
smaller than the larger one of the minimum diameter (D min) and the
length (L) of the molded article of the gas generating
composition.
Inventors: |
YAMASHITA; Haruhiko;
(Tatsuno-Shi, JP) ; Ukita; Shinichiro;
(Tatsuno-shi, JP) ; Hatomoto; Atsushi;
(Tatsuno-Shi, JP) ; Ogawa; Akihisa; (Tatsuno-Shi,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
DAICEL CHEMICAL INDUSTRIES,
LTD.
Osaka-shi
JP
|
Family ID: |
39110741 |
Appl. No.: |
11/947566 |
Filed: |
November 29, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60868849 |
Dec 6, 2006 |
|
|
|
Current U.S.
Class: |
280/736 |
Current CPC
Class: |
B60R 21/261 20130101;
B60R 21/272 20130101; B60R 2021/26011 20130101; B60R 2021/2633
20130101 |
Class at
Publication: |
280/736 |
International
Class: |
B60R 21/264 20060101
B60R021/264 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 1, 2006 |
JP |
2006-325311 |
Claims
1. An inflator comprising: a pressurized gas chamber whose outer
shell is formed by a cylindrical pressurized gas chamber housing,
filled with a pressurized gas; a gas generator being connected to
one end of the pressurized gas chamber, including an ignition
device and a molded article of a gas generating composition in a
gas generator housing; a diffuser portion being connected to the
other end of the pressurized gas chamber, provided with a gas
discharge port; a first communication path provided between the
pressurized gas chamber and the gas generator and closed by a first
rupturable plate; a second communication path provided between the
pressurized gas chamber and the diffuser portion and closed by a
second rupturable plate; a cap having a plurality of gas holes
through which gas passes, the cap being disposed to cover the first
rupturable plate from the pressurized gas chamber side, the minimum
diameter (d min) of the gas hole being equal to or smaller than the
larger one of the minimum diameter (D min) and the length (L) of
the molded article of the gas generating composition.
2. The inflator according to claim 1, wherein an opening portion of
the cap is placed so as to cover the first rupturable plate, a
bottom surface of the cap is placed opposite to the first
rupturable plate, and the plurality of gas holes are formed only on
a peripheral surface of the cap, and the relationship between a
distance (W) formed between the bottom surface of the cap and an
end portion of the closest or proximate gas hole to the bottom
surface of the cap and the minimum diameter (D min) of the molded
article of the gas generating composition satisfies a relationship
of D min/2<W.
3. The inflator according to claim 1, wherein an opening portion of
the cap is placed so as to cover the first rupturable plate, a
bottom surface of the cap is placed opposite to the first
rupturable plate, and the plurality of gas holes are formed only on
a peripheral surface of the cap, and the relationship between a
distance (w) formed between the bottom surface of the cap and a end
portion of the closest or proximate gas hole to the bottom surface
of the cap and the length (L) of the molded article of the gas
generating composition satisfies a relationship of L/2<W.
4. An inflator comprising: a pressurized gas filled with a
pressurized gas and having a first end and a second end; a gas
generator being connected to the first end, and including therein
an ignition device and a molded article of a gas generating; a
diffuser portion connected to the second end, and being provided
with a gas discharge port; a communication path provided between
the pressurized gas chamber and the gas generator and closed by a
rupturable plate; a cap provided to cover the rupturable plate from
the pressurized gas chamber side and having a plurality of gas
holes formed at a circumference thereof, the minimum diameter (d
min) of the gas hole being equal to or smaller than the larger one
of the minimum diameter (D min) and the length (L) of the molded
article of the gas generating composition.
Description
[0001] This nonprovisional application claims priority under 35
U.S.C. .sctn. 119(a) on Patent Application No. 2006-325311 filed in
Japan on 1 Dec. 2006 and 35 U.S.C. .sctn. 119 (e) on U.S.
Provisional Application No. 60/868,849 filed on 6 Dec. 2006, which
are incorporated by reference.
BACKGROUND OF INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to an inflator for use in a
restraint system of a vehicle.
[0004] 2. Description of Related Arts
[0005] A hybrid inflator, in which a solid gas generating agent is
used in combination with pressurized gas, is sometimes employed in
a side impact protection airbag, wherein the gas generating agent
needs to be burned promptly. Therefore, there is known an inflator
having a structure in which a large number of granular gas
generating agents are disposed in a combustion chamber.
[0006] The granular gas generating agents that fill the inside of
the combustion chamber are ignited by an ignition device to start
combustion. The gas generating agents need to be burned completely
within the combustion chamber, but when a large number of granular
gas generating agents are used, half-burned or unburned gas
generating agents flow out of the combustion chamber, whereby
outputs of the inflator fluctuate and the performance of the
inflator is destabilized.
[0007] JP-A No. 2003-226222 discloses a hybrid inflator having a
bottle 22 containing pressurized gas and a gas generator housing 32
containing a gas generating agent. In the gas generator housing 32,
a granular gas generating agent 36 is stored, and it is ignited and
burnt by an ignition device 34. A cap 44 formed, on a side surface,
with a discharge hole 42 is attached to the pressurized gas chamber
bottle 22, and combustion residues or fragments of a rupturable
plate 40 are collected by this cap 44.
[0008] JP-A No. 2001-341610 discloses a hybrid inflator. A first
gas generating chamber 120 and an internal space 103 filled with a
pressurized medium are communicated with each other via a first
communication hole 125 formed on a gas generator housing 105. This
communication hole 125 allows the passage of combustion gas
generated from a gas generating agent 124 and is formed into a size
so as to be able to prevent the gas generating agent 124 from
leaking to the outside.
SUMMARY OF INVENTION
[0009] The present invention provides an inflator including an
inflator comprising:
[0010] a pressurized gas chamber whose outer shell is formed by a
cylindrical pressurized gas chamber housing, filled with a
pressurized gas,
[0011] a gas generator being connected to one end of the
pressurized gas chamber, including an ignition device and a molded
article of a gas generating composition in a gas generator
housing,
[0012] a diffuser portion being connected to the other end of the
pressurized gas chamber, provided with a gas discharge port,
[0013] a first communication path provided between the pressurized
gas chamber and the gas generator and closed by a first rupturable
plate,
[0014] a second communication path provided between the pressurized
gas chamber and the diffuser portion and closed by a second
rupturable plate,
[0015] a cap having a plurality of gas holes through which gas
passes, the cap being disposed to cover the first rupturable plate
from a side of the pressurized gas chamber,
[0016] the minimum diameter (d min) of the gas hole being equal to
or smaller than the larger one of the minimum diameter (D min) and
the length (L) of the molded gas generating composition.
[0017] The present invention also provides an inflator
including:
[0018] a pressurized gas filled with a pressurized gas and having a
first end and a second end;
[0019] a gas generator being connected to the first end, and
including therein an ignition device and a molded article of a gas
generating;
[0020] a diffuser portion connected to the second end, and being
provided with a gas discharge port;
[0021] a communication path provided between the pressurized gas
chamber and the gas generator and closed by a rupturable plate;
[0022] a cap provided to cover the rupturable plate from the
pressurized gas chamber side and having a plurality of gas holes
formed at a circumference thereof, the minimum diameter (d min) of
the gas hole being equal to or smaller than the larger one of the
minimum diameter (D min) and the length (L) of the molded article
of the gas generating composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The present invention will become more fully understood from
the detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention and wherein:
[0024] FIG. 1 shows a cross sectional view of the inflator of the
present invention; and
[0025] FIG. 2 (a) shows a partial enlarged view of FIG. 1, and FIG.
2 (b) is a perspective view of the gas generating agent shown in
FIG. 1.
DETAILED DESCRIPTION OF INVENTION
[0026] JP-A No. 2003-226222 discloses the invention capable of
preventing the combustion residues or fragments of the rupturable
plate from leaking, but does not disclose prevention of leakage of
unburned gas generating agents and specific means therefor. The
invention disclosed in JP-A No. 2001-341610 is an inflator in which
a weight thereof is reduced, the manufacturing processes is
simplified and the gas flow is controlled, but it does not relates
to leakage of the unburned gas generating agents and
destabilization of the performance of the gas generator that is
caused by the leakage.
[0027] Specifically, neither of the JP-A No. 2003-226222 and JP-A
No. 2001-341610 discloses leakage of the unburned gas generating
agents and problems caused by the leakage. The subject solved by
these arts are completely different from that by the present
invention.
[0028] The present invention provides an inflator using a large
number of granular molded articles of a gas generating composition
and pressurized gas, wherein generation of molded articles of a gas
generating composition, which are in the middle of being burned or
in an unburned state is prevented so as to obtain stable
outputs.
[0029] When the inflator of the present invention is applied to an
airbag apparatus, the molded article of the gas generating
composition in a combustion chamber is burned by the activation of
the ignition device, the pressure in the combustion chamber, which
has been the same as the ambient pressure, is increased by the
combustion gas, whereby the first rupturable plate ruptures and the
first communication path is opened. Thereby, high-temperature gas
flows into the pressurized gas chamber via the cap. Then, the
second rupturable plate ruptures when the pressure in the
pressurized gas chamber increases, whereby the second communication
path is opened, thus the pressurized gas and the high-temperature
gas are discharged from the gas discharge hole via the diffuser
portion to inflate the airbag.
[0030] It is preferable that the molded article of the gas
generating composition be burned completely within the combustion
chamber and that only the gas flows into the pressurized gas
chamber. However, since the first communication path is formed
largely in order to secure flow rate and to rupture the first
rupturable plate reliably, some molded articles of a gas generating
composition that are half-burned before being burned completely,
are carried by a gas flow produced by opening the first
communication path and discharged from the combustion chamber.
[0031] To the contrary, the inflator of the present invention is
provided with the cap, and the size of the gas hole of the cap is
associated with the size of the molded article of the gas
generating composition, thus, even when a half-burned molded
article of the gas generating composition is discharged from the
combustion chamber, the half-burned molded article of the gas
generating composition is burned completely inside the cap, and
thereafter only gas is discharged into the pressurized gas chamber.
Therefore, outputs of the inflator are stabilized.
[0032] The gas holes of the cap are preferably formed into a
circular shape, but may be formed into an oval shape or the like.
When forming into a circular shape, the minimum diameter (d min)
indicates a diameter thereof, and when forming into an oval shape,
the minimum diameter (d min) indicates a minor axis.
[0033] A known molded article of a gas generating composition can
be used in the present invention, and a molded article in a shape
of a disk, a column, a column having a through-hole, or a column
having a non-through-hole (hollow) can be used. In the case of a
disk-shaped molded article, the minimum diameter (D min) indicates
a diameter thereof, and in the case of a column, the minimum
diameter (D min) indicates a diameter of an end surface
thereof.
[0034] It should be noted that when the molded article of the gas
generating composition is in the form of a columnar shape, the same
effects can be expected if L>d min is satisfied even when D
min<d min is obtained. Therefore, the minimum diameter (d min)
of the gas hole may be equal to or smaller than the larger one of
the minimum diameter (D min) and the length (L) of the molded
article of the gas generating composition. If a solid gas
generating agent is in a spherical shape, D min=L.gtoreq.d min is
obtained.
[0035] The present invention further provides the inflator, wherein
a side of an opening portion of the cap is placed so as to cover
the first rupturable plate, a bottom surface of the cap is placed
opposite to the first rupturable plate, and the plurality of gas
holes are formed only on a peripheral surface of the cap, and
[0036] the relationship between a distance (W) formed between the
bottom surface of the cap and an end portion of the closest or
proximate gas hole to the bottom surface of the cap and the minimum
diameter (D min) of the molded article of the gas generating
composition satisfies a relationship of D min/2<W.
[0037] In the operation process described above, when the first
communication path is opened and the half-burned molded article of
the gas generating composition is discharged from the combustion
chamber, the half-burned molded article of the gas generating
composition collides with the bottom surface of the cap, that is
opposite to the first rupturable plate (i.e., the first
communication path). Therefore, if the relationship of D min/2<W
is satisfied, the half-burned molded article of the gas generating
composition is completely burned in the vicinity of the bottom
surface of the cap, and thereafter only the gas flows into the
pressurized gas chamber via the gas holes.
[0038] When the above-mentioned relationship is obtained, the
half-burned molded article of the gas generating composition is
easily held (easily caught) in the vicinity of the bottom surface
of the cap. It is preferred in terms of combustion of the gas
generating agent that the half-burned molded article of the gas
generating composition remains in the vicinity of the combustion
chamber as much as possible, even if exists on the outside of the
combustion chamber. Accordingly, the half-burned molded article of
the gas generating composition is burned completely so that it does
not leak to the outside of the cap.
[0039] The present invention further provides the inflator, wherein
a side of an opening portion of the cap is placed so as to cover
the first rupturable plate, a bottom surface of the cap is placed
opposite to the first rupturable plate, and the plurality of gas
holes are formed only on a peripheral surface of the cap, and
[0040] the relationship between a distance (W) formed between the
bottom surface of the cap and a end portion of the closest or
proximate gas hole to the bottom surface of the cap and the length
(L) of the molded article of the gas generating composition
satisfies a relationship of L/2<W.
[0041] When the above-mentioned relationship is obtained, the
half-burned molded article of the gas generating composition is
easily held (easily caught) in the vicinity of the bottom surface
of the cap. It is preferred in terms of combustion of the gas
generating agent that the half-burned molded article of the gas
generating composition remains in the vicinity of the combustion
chamber as much as possible, even if it exists on the outside of
the combustion chamber. Accordingly, the half-burned molded article
of the gas generating composition is burned completely so that it
does not leak to the outside of the cap.
[0042] According to the inflator of the present invention, even
when the all of the molded articles of the gas generating
composition are not completely burned in the combustion chamber and
some of the molded articles of the gas generating composition flow
out of the combustion chamber, they are captured by the cap and
burned inside the cap, whereby gas is generated. Therefore, the
molded articles of the gas generating composition inside the
inflator are burned completely, thus designed outputs are obtained
stably.
PREFERABLE EMBODIMENT OF INVENTION
[0043] One embodiment is described using FIG. 1. FIG. 1 is an axial
sectional view of the inflator of the present invention, FIG. 2(a)
is a partial enlarged view of FIG. 1, and FIG. 2(b) is a
perspective view of a molded article of a gas generating
composition shown in FIG. 1.
[0044] An inflator 10 has a pressurized gas chamber 20, a gas
generator 30, and a diffuser portion 50.
[0045] An outer shell of the pressurized gas chamber 20 is formed
by a cylindrical pressurized gas chamber housing 22, and
pressurized gas including a mixture of argon and helium is charged
therein. The pressurized gas chamber housing 22 has a symmetrical
shape with respect to the axial direction and the radial direction,
thus it is not necessary to adjust the orientation of the
pressurized gas chamber housing 22 in the axial direction and
radial direction when assembling.
[0046] A filling hole 24 for filling pressurized gas is formed on a
side surface of the pressurized gas chamber housing 22, and this
hole is sealed by a pin 26 after the pressurized gas is filled. An
end portion 26a of the pin 26 protrudes into the pressurized gas
chamber 20, and the protruding portion has a length such that a
combustion gas flow of a molded article of a gas generating
composition 36 collides therewith. By adjusting the length of the
protruding portion of the pin 26, the combustion gas can be caused
to collide with the pin 26 itself to adhere combustion residues
thereto. In FIG. 1, the protruding portion can be extended to abut
against a wall surface 22a which is opposite to the end portion 26a
of the pin 26.
[0047] The gas generator 30 has an ignition device (electric
igniter) 34 and the molded article of the gas generating
composition 36 that are accommodated in a gas generator housing 32,
and is connected to one end of the pressurized gas chamber 20. A
space that is filled with the molded articles of the gas generating
composition 36 is a combustion chamber 35. The gas generator
housing 32 and the pressurized gas chamber housing 22 are joined to
each other by resistance-welding at a joint portion 49. When
incorporating the inflator 10 into an airbag system, the ignition
device 34 is connected to an external power source via a connector
and a conducting wire.
[0048] A known molded article of a gas generating composition can
be used as the molded article of the gas generating composition 36.
Since the illustrated molded articles of the gas generating
composition 36 are formed in a columnar shape, the minimum diameter
(D min) thereof indicates the diameter of an end surface.
[0049] A first communication path 38 between the pressurized gas
chamber 20 and the gas generator 30 is sealed by a first rupturable
plate 40 that is deformed into a bowl-like shape by the pressure of
the pressurized gas, and thus the interior of the gas generator 30
is held at an ambient pressure. The first rupturable plate 40 is
joined to the gas generator housing 32 by resistance-welding at a
peripheral edge portion 40a.
[0050] A cap 44 is placed to cover the first rupturable plate 40
from the pressurized gas chamber 20 side. This cap 44 is attached
to cover the first rupturable plate 40 (i.e., the first
communication path 38) so that the combustion gas generated by
burning the molded articles of the gas generating composition 36 is
discharged from a gas hole 42 via the cap 44.
[0051] The cross section of the cap 44 is a circular shape, a
plurality of the gas holes 42 are formed only on a peripheral
surface 44a of the cap 44, and a bottom surface 44b of the cap is
placed opposite to the first rupturable plate 40 (i.e., the first
communication path 38).
[0052] Each of the gas holes 42 formed on the peripheral surface
44a is in a circular shape, and the diameter, d min, is equal to or
smaller than the minimum diameter (D min) of the molded article of
the gas generating composition 36 and is preferably smaller than
the minimum diameter (D min) of the molded article of the gas
generating composition 36.
[0053] The relationship between a distance (W) between the bottom
surface 44b of the cap and an end portion of the closest or
proximate gas hole 42a to the bottom surface 44b of the cap (see
FIG. 2(b)) and the minimum diameter (D min) of the molded article
of the gas generating composition 36 is preferably D min/2<W,
and more preferably D min<W.
[0054] The cap 44 has a flange portion 46 whose peripheral edge
portion of the opening is bent outward, and is fixed by crimping a
part (a crimping portion) 48 of the gas generator housing 32 at the
flange portion 46.
[0055] The diffuser portion 50, that has a gas discharge hole 52
for discharging the pressurized gas and the combustion gas, is
connected to the other end of the pressurized gas chamber 20, and
the diffuser portion 50 and the pressurized gas chamber housing 22
are joined to each other by resistance-welding at a joint portion
54.
[0056] The diffuser portion 50 has a plurality of the gas discharge
holes 52 for allowing the gas to pass therethrough, and is in the
form a cap. A second communication path 56 formed between the
pressurized gas chamber 20 and the diffuser portion 50 is sealed by
a second rupturable plate 58, and thus the interior of the diffuser
portion 50 is held at an ambient pressure. The second rupturable
plate 58 is joined to the diffuser portion 50 by resistance-welding
at a peripheral edge portion 58a.
[0057] Next is described an operation of the inflator 10, shown in
FIG. 1 and FIG. 2, incorporated into an airbag system installed in
a vehicle.
[0058] When the vehicle collides and receives the impact, the
ignition device 34 is activated and ignited by an activation signal
output device to burn the molded articles of the gas generating
composition 36 inside the combustion chamber 35 and generate
high-temperature combustion gas.
[0059] Thereafter, the first rupturable plate 40 ruptures when the
pressure inside the gas generator 30 is increased by the
high-temperature combustion gas, whereby the first communication
path 38 is opened, thus the combustion gas flows into the cap 44,
is then discharged from the gas holes 42, and flows into the
pressurized gas chamber 20.
[0060] Thereafter, the second rupturable plate 58 ruptures when the
pressure inside the pressurized gas chamber 20 increases, thus the
pressurized gas and the combustion gas are discharged from the gas
discharge holes 52 via the second communication path 56 to inflate
the airbag.
[0061] In the operation described above, when half-burned or
unburned molded articles of a gas generating composition 36 are
present inside the combustion chamber 35, they are carried by a gas
flow and discharged into the cap 44 via the opened first
communication path 38. Then, the half-burned or unburned molded
articles of the gas generating composition 36 collide with the
bottom surface 44b of the cap and captured there. In this state,
since the gas generating composition 36 that is not completely
burned exists in the vicinity of the combustion chamber 35, it can
be easily burned completely by the combustion gas (high-temperature
gas) generated from the combustion chamber 35. If the gas
generating composition 36 that is not completely burned passes
through the gas holes 42 of the cap 44 and flows toward the
vicinity of the second communication path 56, the influence of the
high-temperature combustion gas is small, thus combustion is
discontinued.
[0062] As described above, the half-burned or unburned molded
articles of the gas generating composition 36 are prevented from
being discharged from the gas holes 42 of the cap 44 and are burned
completely before the gas generating composition 36 reach the
pressurized gas chamber 20. Therefore, the designed outputs are
realized stably.
[0063] The invention thus described, it will be obvious that the
same may be varied in many ways. Such Variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *